#ifndef __CPPTUTORREQUIRE_H__
#define __CPPTUTORREQUIRE_H__

#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <string>

inline void require(bool requirement, 
                    const std::string& msg = "Requirement failed"){
    using namespace std;
    if (!requirement) {
        fputs(msg.c_str(), stderr);
        fputs("\n", stderr);
        exit(1);
    }
}

inline void requireArgs(int argc, int args, 
                        const std::string& msg = "Must use %d arguments") {
    using namespace std;
    if (argc != args + 1) {
        fprintf(stderr, msg.c_str(), args);
        fputs("\n", stderr);
        exit(1);
    }    
}

inline void requireMinArgs(int argc, int minArgs,
                           const std::string& msg = "Must use at least %d arguments") {
    using namespace std;
    if(argc < minArgs + 1) {
        fprintf(stderr, msg.c_str(), minArgs);
        fputs("\n", stderr);
        exit(1);
    }
}
  
inline void assure(std::ifstream& in, 
                   const std::string& filename = "") {
    using namespace std;
    if(!in) {
        fprintf(stderr, "Could not open file %s\n",
        filename.c_str());
        exit(1);
    }
}

inline void assure(std::ofstream& out, 
                   const std::string& filename = "") {
    using namespace std;
    if(!out) {
        fprintf(stderr, "Could not open file %s\n", 
        filename.c_str());
        exit(1);
    }
}
#endif // __CPPTUTORREQUIRE_H__ ///:~
